Potions can be used in Torchlight to either regain health or mana, or to increase statistics. There is also a potion to refund all skillpoints the player has spent on their character.
Gold is dropped from most monsters and is used as the basic currency of the game. Gold is used to buy potions, scrolls, weapons, armor, enchantments, etc.
Torchlight has a number of Sets. Sets are composed a a number of items, usually armor and weapons, that when worn together have a synergistic effect (that is they are more powerful). Sets come in two levels; 'ordinary' and 'Epic'. The 'Epic' versions have much higher requirements to use.
Fish can be caught by the player from fishing holes that can be found in random areas of the game, a preset fishing hole can be found in town. Fish are caught by interacting with the fishing hole and playing a mini-game.
The main use for fish in Torchlight is to transform your pet into different types of creatures to give him different abilities and/or change his appearance. Some fish can instead be consumed by the player for an attribute bonus, and other fish can contain items, and can even contain other fish.